The present invention relates to a semiconductor device and, particularly, to a semiconductor device having a fuse program circuit including a fuse element that stores fixed information. More specifically, the invention relates to a configuration for realizing a fuse program circuit capable of reliably cutting a fuse element with low power consumption and smaller occupation area and performing a cut state determination.
In a semiconductor integrated circuit device (semiconductor device), a fuse program circuit is used for various applications. A state of an output signal of the fuse program circuit is fixedly set according to whether a fuse element is cut or not. For example, to finely adjust the constant of an analog circuit (trimming), such a fuse element is used. Concretely, the fuse element is programmed (cut or not) in order to perform adjustment of current drive force of a transistor element, adjustment of a supply current amount of a reference current source, and/or adjustment of a reference voltage level generated by a reference voltage supply. Such a fuse program circuit is used also for finely adjusting a resistance value of a resistive element.
Adjustment similar to such adjustment of an analog value is also performed in a digital circuit. In a semiconductor memory, it is necessary to program an address for specifying a defective cell in order to replace a defective cell with a redundant cell. To store such an address, a fuse program circuit is used. By using such a fuse program circuit, optimization of the circuit operation characteristics is realized regardless of an analog circuit and a digital circuit, and the yield is improved by repairing a defective cell in a semiconductor memory.
The configuration of a fuse program circuit including a line cutting type electric fuse element for cutting a fuse element by current in such a fuse program is disclosed in patent document 1 (Japanese Patent Application Laid-Open Publication No. 2007-317882). In the configuration described in the patent document 1, a fuse is formed by using a wire in an upper layer in a multilayer metal wiring layer, and a preventing wall is formed so as to surround the fuse. The fuse is made by a copper (Cu) wire, and occurrence of poor cutting due to diffusion of copper after the cutting is suppressed by a preventing wall structure. Just above a fuse element, a wire configuring a node coupled to a transistor that passes current for cutting the fuse element is disposed. A power supply wire for supplying a power supply voltage is disposed in a layer above the wire configuring the node.